Answer:
Organ system → Circulatory system
Organ → Heart
Tissue → Cardiac muscle
Step-by-step explanation:
The human body is a complex set of various organ systems. An organ system is a set of organs that work in a coordinated manner to perform various functions.
The circulatory system, for example, is made up of two systems: the lymphatic system (which carries lymph to the heart) and the cardiovascular system (which takes care of the blood flow throughout the body).
Thus, the circulatory system is formed by the heart, capillaries, veins, arteries, lymphatic vessels, thymus, spleen, lymph nodes, lymphatic tissues and bone marrow.
Organ, in turn, is a structure formed by a group of tissues that perform a specific function or group of functions.
For example, the heart, whose primary function is to pump blood throughout the body.
Tissues are sets formed by similar cells. Each type of tissue is capable of performing a specific function. Each organ may consist of one or more tissues.
The cardiac muscle tissue, for example, is responsible for involuntary contractions (regardless of one's will) of the heartbeat in a vigorous and rhythmic manner.